Set Specific Bits in a 32-bit Register

Code

#include <stdio.h>
#include <stdint.h>

uint32_t set_bits(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    uint32_t mask = ((1u<<len)-1)<<pos;
    return reg|mask;
}

int main() {
    uint32_t reg;
    uint8_t pos, len;
    scanf("%u %hhu %hhu", &reg, &pos, &len);
    printf("%u", set_bits(reg, pos, len));
    return 0;
}

Solving Approach

Initialize a variable mask. Mask variable = uint32_t mask = ((1u<<len)-1)<<pos; Lets say len=4, it will make the number ...10000.  1 is subtracted form this making it ...01111. Now 4 bits are set and we need to shift to the starting position hence left shifitng by pos.